A seat belt device is designed to restrain a passenger to a seat of a vehicle by the use of a webbing drawn out from a retractor, thereby protecting the passenger at the time of collision of the vehicle or the like. In the seat belt device, when an acceleration greater than a predetermined value acts in the horizontal direction, a locking device is actuated to stop rotation of a retractor spool.
As an acceleration sensor for detecting the acceleration, there is known an acceleration sensor having a sensor weight which rotates in a reclining direction by means of the acceleration in the horizontal direction and the tilting of the vehicle. In addition, there are known a variety of electrical or electronic acceleration sensors.
By fitting such a seat belt retractor into a seat backrest, the belt can be attached and detached regardless of the reclining angle of the backrest.
However, when the seat belt retractor having the sensor-weight type acceleration sensor is fitted into the backrest and the backrest is reclined in the reclining direction, there is a problem that the sensor weight is also reclined and the locking device is activated. Accordingly, the retractor spool becomes locked and therefore webbing cannot be drawn out.
Therefore, in the retractor mounted in a seat backrest, there have been suggested a variety of mechanisms for keeping the sensor weight horizontal by allowing the sensor-weight type acceleration sensor in the retractor to interlock with the tilt of the backrest. For example, there is known a seat belt device disclosed in the followings.
However, in order to realize a wide operation angle with respect to the reclining angle of the backrest, the conventional seat belt device has a problem in that the number of parts should be increased and an assembly process such as positioning the parts is complicated, thereby increasing the manufacturing cost.
The invention seeks to solve the above-mentioned problem. An object of the invention is to provide a seat belt device which can reduce the manufacturing cost.
In order to accomplish the above-mentioned object, a seat belt device according to a first aspect of the invention includes a seat belt that can be drawn out and wound up so as to restrain a passenger in a vehicle to a seat; a locking device for locking an operation of drawing out the seat belt as needed; an acceleration sensor for actuating the locking device; an angle detection device for detecting a reclining angle of a backrest of the seat; and an acceleration sensor controller.
It is preferable that the sensor controller includes a posture controller for orienting the acceleration sensor in the vertical direction, and an interlocking member for allowing the posture controller to interlock with the angle detection device. It is preferable that the interlocking member may be a flexible cable.
It is preferable that the sensor controller further a sensor deactivator that detects a winding amount of the seat belt when the reclining angle is within the range where the passenger does not wear the seat belt and deactivates the acceleration sensor.
Here, the backrest can be reclined forward and backward, for example, by about 90 degrees with respect to a vertical direction assumed as substantially 0 degree. A position where the backrest is reclined by a predetermined angle with respect to the vertical direction is set as an initial position of the backrest. A range where the passenger does not wear the seat belt is a range where the backrest is reclined forward by about 10 degrees or more from the initial position, and a range where the passenger wears the seat belt is a remaining range.
It is preferable that the backrest of the seat is rotatably connected to a seating portion on which the passenger sits and the acceleration sensor is a sensor-weight type acceleration sensor mounted in the backrest of the seat. Further, it is also preferable that the angle detection device is a link mechanism that is disposed in a connecting portion between the backrest and the seating portion of the seat so as to detect a rotation angle of the backrest and to rotate the interlocking member of the sensor controller in accordance with the reclining angle.
According to the sensor controller, on the basis of the detection result from the angle detection device, the posture controller controls the acceleration sensor to be kept horizontal by means of the rotation of the interlocking member when the reclining angle is within the range where the passenger wears the seat belt, thereby setting the acceleration sensor in an operable state.
The posture controller does not interlock with the angle detection device when the reclining angle is within the range where the passenger does not wear the seat belt, thereby setting the acceleration sensor in an inoperable state by the use of a sensor deactivator.
According to the seat belt device having the above-mentioned configuration, since the link mechanism is used as the angle detection device, it is possible to reduce the number of parts. In addition, a complicated assembly process is not necessary. As a result, it is possible to reduce the manufacturing cost.
According to the sensor deactivator, when the backrest is intended to rise from the range where the passenger does not wear the seat belt, such as the position where the backrest is reclined most forward, to the range where the passenger wears the seat belt, it is possible to avoid the locking to a state that the seat belt cannot be drawn out, due to the actuation of the acceleration sensor.
It is preferable that the angle detection device includes a first detection member, a second detection member, a first link member, and a second link member.
The first detection member is fixed to the seating portion of the seat so as to detect the rotation angle of the backrest. The second detection member is fixed to the backrest so as to detect the reclining angle of the backrest and is connected to the first detection member by means of a first linkage. An end of the first link member is connected to the first detection member by means of a second linkage. An end of the second link member is connected to the other end of the first link member by means of a third linkage, and the other end thereof is connected to the second detection member by means of a fourth linkage.
The rotation of the second link member by the fourth linkage is transmitted to the posture controller through the interlocking member. It is preferable that interlocking member is a flexible cable.
It is also preferable that the angle detection device is housed in the second detection member that also serves as a housing case.
According to the seat belt device having the above-mentioned configuration, it is possible to further reduce the number of parts. In addition, a complicated assembly process is not necessary. As a result, it is possible to further reduce the manufacturing cost.
It is also preferable that the posture controller comprises a sensor-weight casing, a cam groove, and a posture control lever. The sensor-weight casing houses a sensor weight and is pivotably mounted in the backrest. The cam groove is formed in the sensor-weight casing. The posture control lever slides in the cam groove by means of the interlocking member.
The posture control lever slides in the cam groove so as to keep the sensor-weight casing horizontal when the reclining angle is within the range where the passenger wears the seat belt.
The sensor control lever does not interlock with the angle detection device when the reclining angle is within the range where the passenger does not wear the seat belt, thereby not keeping the sensor-weight casing horizontal.
A seat belt device according to a second aspect of the invention includes a seat belt for restraining a passenger in a vehicle to a seat and a retractor for drawing out and winding up the seat belt. The retractor includes a locking device for locking an operation of drawing out the seat belt as needed, an acceleration sensor for actuating the locking device, and a posture controller for controlling a posture of the acceleration sensor. The seat belt device further includes an angle detection device for detecting a rotation angle of a backrest of the seat; and an interlocking member for allowing the posture controller to interlock with the angle detection device.
Here, it is preferable that an initial position of the backrest of the seat is a position where the backrest is reclined backward by a predetermined angle with respect to a vertical direction, and the interlocking member does not interlock within a range where the backrest is reclined forward by about 10 degrees or more from the initial position. It is also preferable that the backrest of the seat is rotatably connected to a seating portion on which the passenger sits and the acceleration sensor is mounted in the backrest of the seat and the angle detection device is a link mechanism that is disposed in a connecting portion between the backrest and the seating portion of the seat so as to detect the rotation angle of the backrest and to rotate the interlocking member in accordance with the reclining angle.
It is also preferable that the posture controller controls the acceleration sensor to be kept horizontal by means of the rotation of the interlocking member when the reclining angle is within the range where the passenger wears the seat belt. On the other hand, it is also preferable that the posture controller does not interlock with the angle detection device when the reclining angle is within the range where the passenger does not wear the seat belt.
It is also preferable that the retractor further comprises a sensor deactivator that detects a winding amount of the seat belt when the reclining angle is within the range where the passenger does not wear the seat belt and deactivates the acceleration sensor.
According to the seat belt device having the above-mentioned configuration, since the link mechanism is used as the angle detection device, it is possible to reduce the number of parts. In addition, a complicated assembly process is not necessary. As a result, it is possible to reduce the manufacturing cost.
According to the sensor deactivator, when the backrest is intended to rise from the range where the passenger does not wear the seat belt, such as the position where the backrest is reclined most forward, to the range where the passenger wears the seat belt, it is possible to avoid the locking to a state that the seat belt cannot be drawn out, due to the actuation of the acceleration sensor.
It is preferable that the acceleration sensor is a sensor-weight type acceleration sensor and the retractor further includes a sensor-weight casing that houses a sensor weight of the acceleration sensor and is pivotably mounted in the retractor and a posture control lever that is activated by the interlocking member. A cam groove in which the posture control lever slides is formed in the sensor-weight casing. The posture control lever slides in the cam groove so as to keep the sensor-weight casing horizontal when the reclining angle is within the range where the passenger wears the seat belt.